This invention pertains to insertion machines, and in particular to machines wherein an individual piece of material is pneumatically or otherwise deflected from a stack containing a plurality of pieces to facilitate eventual extraction and deposition of the individual piece onto a transport means.
U.S. Pat. No. 2,325,455 to A. H. Williams, incorporated herein by reference, discloses an insertion machine having a chain-like transport means powered by a rotating shaft in conjunction with various intermediate shafts and gears. Initially the transport means is indexed past a plurality of supply stations, including an envelope supply station and insert supply stations, from which corresponding materials are extracted and deposited onto the transport means. The transport means is then indexed past other stations which sequentially perform numerous individual functions, including opening an envelope flap; positioning the envelope at an inserting station; opening the envelope; inserting material into the envelope; moistening the envelope flap; closing the envelope flap; and, affixing a stamp to the envelope.
The supply stations described in the Williams patent and subsequent related devices include supply tables, or hoppers, having vertically stacked thereon numerous pieces of material, such as envelopes or insert material. Beneath each supply table is a selector comprising one or more sucker cups. Once during each machine cycle, a time period gauged by the rotational cycle of the machine, the selector moves first upwardly into the plane of the supply table and then downwardly therefrom so that, when a vacuum is applied through the sucker cups, the selector downwardly deflects an edge of the lowermost piece of material stacked on the table.
While the edge of the lowermost piece is being deflected in the above manner, a separation mechanism associated with the supply station interposes itself between the selector and the bottom of the supply table. Although the vacuum applied through the selector sucker cups may cease at this point, the edge of the lowermost piece remains deflected and is prevented by the separator mechanism from returning to the supply table.
Also associated with the supply station is a gripper jaw mechanism which swings inwardly beneath the supply table; engages the deflected edge of the lowermost piece between the gripper jaws; extracts the lowermost piece as it swings away from the supply table; and, deposits the piece of material on the transport means After deposition on the transport means in this manner, the piece of material is ushered downstream during the next machine cycle where other sequential functions, such as those mentioned above, are performed.
Although the operation as basically summarized above is efficient and advantageous when compared to other types of insertion mechanisms, problems do occur if the selector associated with any supply station either fails to deflect the lowermost piece of material contained therein (a "miss") or deflects other pieces of material in addition to the lowermost piece (a "double"). Such faulty operation of the selector may be either a random occurrence or, more seriously, a continuing mechanical malfunction of the selector such as, for example, an improper adjustment of vacuum pressure.
Unless the selectors are continually monitored, it is improbable that the malfunctions described above will be detected in time to be rectified. As a result, the selectors may preform erratically by either wastefully deflecting too many pieces or failing to deflect any pieces at all.
Even when the malfunction of a selector is detected, rectification of the malfunction is painstaking and costly. Typically, the entire insertion machine must be shut down while an operator attempts to manually locate and correct the situation. Deactiviation of the machine in this manner, even for a brief period of time, requires numerous machine cycles and, therefore, involves a significant lost volume of production.
Various insertion machines currently available detect double or miss errors, the more significant of these devices including those embodied in the following U.S. Pat. Nos. 3,744,787 and 3,885,780 to Morrison, and 4,013,283 and 4,132,402 to Tress et al. These devices basically gauge the amount of material extracted from a supply station by either (1) determining the degree of jaw separation when a gripper jaw is employed, or (2) determining the degree of roller separation when a pull-foot mechanism is employed. In either type of device, the degree of separation is transmitted by a moveable electrode which grounds double or miss electrical contacts when a malfunction occurs. An object of this invention, however, is to provide an alternate means for accurately monitoring the selection of pieces of material from a supply station of an insertion machine.
An advantage of the invention is the provision of means to permit the selector means of an insertion machine to quickly and automatically correct random malfunctions of the selector means.
Another advantage of the invention is the capability of distinguishing between the random, correctable malfunctions of a selector means and the continuing mechanical malfunction of the selector means.
Accordingly, a further advantage of the invention is the temporal and financial economy realized in efficiently monitoring and maintaining an insertion machine without manual intervention.